Berlin 2018 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 3: Complex Fluids and Colloids I (joint session CPP/DY)

DY 3.2: Talk

Monday, March 12, 2018, 09:45–10:00, C 264

Unification of Lower and Upper Critical Solution Temperature Transitions in Aqueous Protein Solutions — •Nafisa Begam, Stefano Da Vela, Fajun Zhang, and Frank Schreiber — Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen

Phase separation in aqueous protein solution is of primary interest in the field of many biological and chemical processes. In particular, phase separated protein solutions exhibiting lower/upper critical solution temperature (LCST/UCST) behavior have been of significant importance in the food and pharmaceutical industries. Based on theoretical calculations [1] and experimental observations, it is predicted that proteins can be designed with tunable LCST and UCST. Here, our goal is to experimentally design such aqueous protein system showing tunable LCST and UCST transitions. The UCST phase of β-Lactoglobulin - Yttrium Chloride (YCl₃) based aqueous systems at a salt concentration higher than a critical concentration, c*, has been already reported by our group [2]. However, we obtain evidence of LCST phase behavior of this system at a lower salt concentration but higher than c*. The solution becomes turbid at high temperature and clear at low temperature. Similar indication of the presence of both LCST and UCST phase behavior we get from the SAXS measurements on Bovine serum Albumin (BSA) - YCl₃ system. The findings of this study suggest a controllable dual phase of aqueous protein solution by tuning the ionic strength. [1] Jianguo Li et. al, J. Chem. Phys., 128, 235104, (2008) [2] F. Zhang et. al, J. App. Crystal., 44,755-762, (2011)